Manufacture of celluloid or the like.



s'rn'rns PATENT onmon.

THOMAS BOLAS, OF

No Drawing;

. To all whom it may concern:

Be it known that I, THOMAS BoLAs,a sub ect of the King of Great Britain, residing at 60 Grove Park Terrace, Chiswick, in the county of Middlesex, England, have invented certain new and'uscful Improvements in the Manufacture of Celluloid or the Like, of

a suitable solvent that the sheet will, on drymg, become compact, structureless or fiberless and transparent,

The present invention has for its object the formation and mode of using a sheet or sheets of pgroxylin so completely gelatinized' by a suite le. solvent that the structural or ii rous character thereof is lost or destroyed; a compact transparent sheet of pyroxylin suitable for use as a base for photographic emulsion being obtained b means involving far less expenditurevof so vent than obtains when films or sheets are made by castingor flowing with a solution of'pyroxylin. Further, in many cases there is a saving of labor and consequent cost in the process of manufacture with the advantage of a superior product; a product which is harder, more elastic, and'more inert chemically than the usual sheets or films of celluloid sold for photographic purposeswhich ordinarily contain much camphor.

I am aware of many early attempts to industrially realize the agglomeration of pyroxylin into a compact mass but all these differ in essential features from the present invention. Thus for example at one ofthe Cantor lectures delivered by the present applicant before the Society of Arts on'the 30th February, 1880, there were dis layed and described several samples of co luloid articles which had been formed by pressure from pyroxylin that had been moistened with a solvent, and in the rinted version that appears in the Jdurna 0 f the Society of Arts dated the 27th August,'l880, it was stated Another CQlllllOld-likfl body, due to the ingenuity of Mr. Parkes, of Birmingham, is

- obtained by softening Intro-cellulose by means of alcohol and forcing the product in o molds. This substance is exceedingly .igh, while it has the advan age of being Specification of Letters Patent.

Application filed October 3, 1908. Serial No. 456,084.-

CHISWICK, ENGLAND, ASSIGNOR TO SELF-DEVELOPING PLATE COMIANY LIMITED, 0]? HOLBORN, ENGLAND.

MANUFACTURE OF CELLULOID OR THE LIKE.

Patented July 19, 1910.

free from camphor, and-is capable of resisting the action of heat to a considerable extent.

There have been and are many uses of sheets of complete or made elluloid softened by a solvent, but these are extraneous to my invention em a solvent to gelatinize .an original sheet or nitrated fibrous material and thus to give it for the first time its celluloid-like compact or iinpervious character. In short i do not softena sheet of celluloid-like material by my softening or gelatinizing process, but pro duce the celluloiddike character'of my sheet pyroxylin by the use of an amount of high or complete solvent insufficient to dissolve the material, and at the same time T retain the sheet like form; this change it will be noted is effected by the solvent independently of any kneading stress or pressure.

The purification or treatment of masses or grains of pyroxylin, by the action of a partial solvent or a solvent mixed with an inert fluid, is known to me but this in no way bears on the present invention as my method only applies to sheets of the original nitrated material retaining the original form, and, as will be realized from the description hereinafter given, my invention is only applicable to sheets, and indeed to sheets of very thin substance. Moreover my method requires complete or perfect solvents used in moderate quantity or in quantity insuflicient to totally dissolve the solid, the practical problem in the successful Working of my method being to produce the maximum of gelatinizing effect with a minimum of solvent this being applied by spraying, flowing or the like. It has also been proposed to use a solvent on compressed masses of nitro-cellulose to harden and varnish the surface. Here again however the process is quite distinct from mine-which depends on the use of uniformly thin sheets, and complete or thorough gelatinization by the solvent.

.The raw material or sheet cellulose l1av= ing been nitrated in a usual manner by a mixture of acids is subsequentlygelatinized.

For the purposes of my invention the said material should be thin, even in texture, and as pure chemically as possible. ,It may be paper, linen, cotton cloth, )apyrus or the like, but of an the materials hitherto used I i prefer the chemically pure filter papers as sold for laboratory use, as, for example, the pure white English filtering paper mill No. 633 which has given highly satisfactory results, the thickness being such that a sheet '24 inches square weighs about 333 grains,

corresponding to lbs. to the ream or thereabout. I do not however confine myself to this weight as I have used with equal success a similar paper of five times the,

. and the combining of several or many layers of the nitrated paper before or after gelatinization by a solvent is expedient when I require a thick product; with thinner paper than that mentioned above, as, for example, tissue paper, the result is good by reason of rapid and complete nitration but extremely thin paper is inconvenient to handle. The paper, which should bein a completely dry state, is now immersed in or slowly passed through a nitrating mixture of the known kind, such-as a/inixture of nitric acid and sulfuric acid or of sulfuric acid and nitrate of potash or nitrate of soda. As an example I give the following: sulfuric acid, of specific gravity 1.843, one volume nitric acid, of specific gravity 1.42, one

. volume.

On mixing, the temperature rises somewhat; ordinarily to 120 Fahr. or 130 Fahrand the mixture may be used at this tem-' perature or it may be allowed to cool. .The paper is now passed or drawn slowly through the mixed acids, a course which would naturally be followed in working with a roll or reel of the paper. When, however, sheets are being employed it will generally be convenient toimmerse the sheets completely. Three minutes in the acid mixture may be sufficient for the thin (20 lb.) paper mentioned above, but longer is desirable as giving a more glass like. and clear product. Ordinarily the paper may remain in the acid mixture for twelve hours or more without harm resulting, but speaking generally the best time of immersion is from ten to fifteen minutes for 20 to 30 lb. filtering or blotting paper of the kind referred to; harder or thickeranaterial will require longer. Should opalescentor whitish patches show'when. the solvent has acted on the nitrated paper the indication is that .of insuflicient nitration.

On removal from the acid mixture the nitrated cellulose or pyroxylin, whether in the form of a band. or sheets, is well Washed, and an alkaline addition may be made to the wash waters; when the water has been dried. off or removed, say, by soaking in alcohol, by exposure to the air or by heat or in any 'other well known way, the said. paper is access necessaryto the success of the treatment, but

it is to be understood that no.- particular means of supporting are to be re arded as formingpart of this invention. sheets at nitrated cellulose (sheets as distinguished from aband) are being treated the support ordinarily used is a slab of glam,

--marble or'oth'er convenient or like material.

This slab may be rubbed over with French chalk to diminish any subsequent tendenc to adhesion, it is then leveledgfioodedwith a thin layer of the solvent andthe sheet of nitrated cellulose is laid upon'the layer of solvent which now penetrates and elati: nizes the sheet. i lhen dryt-he celluloid like and transparent sheet of pyroxylin is removed or peeled away from the support. When a celluloid sheet, or celluloid like sheet of greater thickness is required several sheets of nitrated cellulose are laid down as a group .upon the slab and gelatinized, or they may be laid down in succession on the slab, the slab being a ain flooded with solvent 'beforeeach additional sheet of nit-rated cellulose is laid down. The thickened or composite sheet of pyroxylin is then allowed to dry on the slab after which the compound sheet is peeled ofi.

When the nitrated cellulose is in the form of a roll or band, as it is gelat-inized it may be received on slabs of glass or other rigid material the. solvent bein sura ed or allowed to flow on the nitrated cellulose as it reaches the slab, the slab being drawn for ward to keep pace with the unwinding of the roller. i l hen, however, long bands of the product are required the gelatinized material is bestreceived on a flexible band which may be composed of metal, gelatinor the like. An alternative method is to receive the gelatinized nitrocellulose on a warm roller from which it passes'to other warm rollers thereby drying leveling it. Instead of the rollers I may employ an endless band of flexible metal or material, this losing warmed by steam boxes or the like. The method of working with bands and of drying or mechanical treatment herein referred to' being well known in connection with ordinary celluloid and other impervious methods no general claim is made in respect thereof; they are referred to the present description as hearing on the manner in which the herein described sheet of pyroxylin may be handled or treated before or after having been 'moistened with the solvent whereby it is gelatinized or its fibrous'structure so de- 1 flooding a plate or-s1ab,with a solvent of on the support as alrea render it suitable for the emulsion or in any other way known to stroyed as to make it compact and impervious. i

. WVhen the gelatinized pyroxylin sheet ,is allowed to dry on the glass or other slab it will generally be found on stripping or peeling off the material, that the side which has been in contact with the glass or other support is smoother than the upper or outer side. This upper side may be smoothed by rolling, burnishing or calendering. If preferred the rougher side may be smoothed by pyroxylin, and laying the sheet, rougher side downward on the flooded side of the slab. When again dry the material is oncemore stripped or peeled ofl". Another method of smoothing the rougher surface of the pyroxylin sheet is to flood the said surface with a warm solution of gelatin while the material is still on its support, and when the gelatin is dry or nearly sothe film is peeled off with the stratum of gelatinstill adhering to the pyroxylin and laid the elatined side down 5y described, but in this case water and not a solvent of pyroxylin must be employed to soften the surface and establish adhesion between the gelatincoated surface and the surface of the sup- Dort. l The herein described celluloid-like film may be coated with sensitive emulsion tophotographic .purposes, the operation being performed by flowing the emulsion over the celluloid-like film while on its support or by drawing the film over a roller revolving in a trough of experts. V

By the term sold'ent of pyroxylin, I mean any liquid capable of dissolving thematerial and I may useany one of the many sim ple or mixed solvents commonly employed. Ordinarily I prefer amyl acetate or'a mixture of amyl acetate with acetone; with or without an addition of camphor in either case. A coloring matter can be added to they solvent when a colored product is required. I

It is within my knowledge that many proposals-have been made for rendering blotting paper or the like translucent by various agencies such as the treatment in which resinous products are incorporated, and upon which the transparency depends; also the uniting or agglomeratin g of sheets ofnitrated' paper while in an acid bath. Such a mode of procedure would,-however, fail in securing the object aimed at in the present invention, viz equal nitration, facilities for the removal of acid and complete gelatinization of the sheets by the action of a high solvent.

I make no general or universal claim to the use of flexible bands or sheets as supports for soft materials of the celluloid class 'as there have been numerous proposals in this connection.

As regards my use of a stratum of gelatin .on my celluloid material, and the fact that this stratum of gelatin would ordinarily be at the back of my film when coated with photographic emulsion as described, I may state that my object in so using gelatin is to somewhat fill or level the less even surfaces of the material, previous to the transfer in reversal above referred to. Composite films of celluloid and gelatin are well known in relation to photographic uses, indeed the ordinary and well known non-curling roll film is a combination of this class and many patents have been granted relating to stratified combinations of celluloid and gelatin.

What I claim and desire to secure by Letters Patent of the United States is 1. The method of manufacturing transparent sheets of pyroxylin or the like suitable for use as a basis for photographic emulsion consisting in producing a uniformly nitrated pyroxylin" in sheet form, rendering the sa'me transparent by treatment with a solvent, supporting the same until dry, then subjecting the sheet of dried pyroxylin to a gelatinous solution or liquid which shall smooth or render the whole uniform, and thenv to reversal on the means of support for the purpose of smoothing the ,iaces of the said sheet.

I 2. The method of manufacturing a detached transparent sheet or film of pyroxylin suited as a base for photographic emulsion, by treatin very thin nitratedmlaterial with a spray o solvent, so as toharden and compact the sheet, and with the aim of producing a detached sheet.

In testimon whereof I ailix my signature in presence 0 two witnesses.

. THOMAS BOLAS. Witnesses:

T. SELBY WARDLE, T. J. OsMAN. 

